Remove an errant newline from the dirs function

The dirs function prints an extra newline; it is not obvious why this is
needed but it has been this way forever. Let's remove it.

share/functions/dirs.fish

@@ -16,5 +16,4 @@ function dirs --description 'Print directory stack'
 
     # Replace $HOME with ~.
     string replace -r '^'"$HOME"'($|/)' '~$1' -- $PWD $dirstack | string join " "
-    echo
 end